The invention relates to an apparatus having a screen for showing a plurality of pictures, each being composed of picture segments on at least two groups of horizontal strips, the strips in each individual group being made in one continuous sheet and being separated from one another by horizontal cutting lines extending between two marginal portions of the sheet. The various sheets are placed one upon the other, in such a manner that the strips carrying the picture segments are gathered in a number of piles which are equal to the number of strips in each sheet. The number of strips in each pile is equal to the number of picture forming groups, and each single sheet--with the group of strips formed therein--is displaceable in a plane relative to the other sheets, i.e. relative to the other strips in the piles, in such a manner that the picture segments on them become visible and together with picture segments on at least one more displaced group of strips in another sheet, form a continuous picture.
The word "cassette" as used herein meant to denote an easily replaceable unit comprising a plurality of groups of strips, where the strips in each group form a picture and the strips in the different groups overlap each other in a louverlike manner and are mutually displaceable by simultaneously moving all strips in one and the same group relative to all other groups. In this way edge portions of the strips in the group in question will become visible and together with edge portions of other displaced stirps form a complete picture.
In known cassettes of this type, each strip is suspended in straps which are moved up and down by guide means which displace picture carrying edge portions of the individual groups of strips into a visible position in order to display a number of pictures sequentially (see Danish Patent Application No. 369/70 or U.S. Pat. No. 3,613,277). This method of suspending and moving the picture carrying strips is rather complicated. It has the effect that the cassette becomes rather thick, and each individual picture must be composed of relatively narrow edge portions on three or more groups of strips. This is because each strip can only be displaced along a fraction of its height, since the strips of the different groups which together form a picture, must overlap each other like louvers, in a position of rest, as well as in a position of display.
Further, from U.S. Pat. No. 3,659,367 it is known to use two sheets, each of which is divided into a plurality of picture carrying strips by means of cutting lines which at their ends join a short cutting line situated perpendicularly to the first cutting line in the marginal portion of the sheet. By mutual displacement of the sheets two different pictures can be shown alternately, but it is not possible to produce a greater number of pictures, e.g. 5 or 6 pictures successively, with one single cassette.